1. Field of the Invention
The present invention relates to a splice casing assembly for splicing a first length of fiber optic cable to a second length of fiber optic cable, and for providing strain relief to tensile loads applied axially along the cable. The splice casing assembly is particularly useful with low fiber count cable.
2. Description of the Prior Art
The use of optical fiber waveguides to transmit light energy is quite diverse. For example, there are telecommunication, data, Local Area Network (LAN), and military applications, to name some of the present day uses. In such applications it is not uncommon to require the coupling of fibers in end-to-end relationship. To this end, optical splices are used. For example, optical splices are used to join optical fiber lengths which are individually too short. Similarly, such splices are used during restorations to quickly and easily repair fiber breaks. However, such coupling of fibers is a source of light or signal loss. Any axial misalignment presents a particularly serious problem in signal loss. Other factors causing signal loss include angular misalignment of fibers, axial separation of adjacent fiber ends and reflections or refraction of fiber ends.
In coupling optical fiber lengths it is desirable to have a splice which can be readily used in the field, can be depended upon to properly align the constituent fibers, serves to protect the spliced area from environment factors, and secures the splice in place for any length of time. U.S. Pat. Nos. 4,512,628 and 4,556,281 to Anderton and assigned to the assignee of the present invention provide respective known splice casing assemblies of the type contemplated herein. The present invention is an improvement over the splice casings of these two patents, the splice casing assembly described and claimed herein believed to provide expanded capabilities, improved performance and enhanced user friendliness.
In considering the prior art represented by the U.S. Pat. Nos. 4,512,628 and 4,556,281 patents, typically the strength members and/or the fibers are threaded through a casing plug. This is a time consuming procedure. It is desirable to provide a corresponding casing plug around which the strength members and fibers can be guided rather than inserted therethrough, thereby easing assembly. A further reason for desiring such guiding is that a slight excess in fiber length can be introduced during assembly. This additional length can be large enough to endure small tensile loads, and small enough so as not to induce microbending, without loss of power through the splice.
Similarly, in prior art structures, the strength members of the fiber optic cable have been tied in such a manner as to be off the axis of the cable, and individual strands of the strength members have been subjected to preferential stress. It is desirable that the strength members be tied in an orientation completely axial with the cable and therefore entirely on the line of stress so that the full amount of the strength members will be pulled in tensile conditions thereby taking advantage of the total tensile strength of the cable. It is also desirable that the individual strands which comprise the strength members not be preferentially stressed.
It is also desired to provide a splice casing assembly which will direct the fibers and strength members such that they are not forced around sharp corners or positioned in a manner likely to cause fraying of the strength members or microbending of the fibers.